The present invention relates to a flange protector adapted to be placed on a flanged joint to protect the flange gasket as well as the flange bolts and interior flange surfaces from the environment.
Flanged type fittings are common in various piping related industries, such as the chemical and petroleum recovery industries. Such fittings include a sealing ring or gasket interposed between a pair of flanges, with connecting flange bolts holding the flanges together and forming a seal between the flanges and the flange gasket. In many applications, the flange bolts are torqued to a desired extent to form the proper seal, with the flange interior surfaces being spaced slightly apart. Such spacing is desirable in order to insure that the two flange surfaces can vary within normal manufacturing tolerances, yet do not engage to limit the force exerted on the seal between the flanges.
It may be understood that air may enter the space between the flanges and corrode the sealing ring, the flange bolt, and the interior of the flange faces. In many applications, such corrosion is not a serious problem and a flange protector of one type or another may not be required. In corrosive environments, however, such as salt water or sour gas environments, such corrosion can be severe and may cause major repair problems. Corrosion of the metallic sealing gasket may cause a massive leak in the pipeline, and corrosion of the interior flange surfaces and the flange bolts can similarly cause both significant expense for repair of the damaged equipment and the loss of production for such repair operations.
The flange protector of the present invention is distinquishable from leak repair devices which temporarily stop leakage from a flange. A flange protector is installed to reduce or prevent flange and seal deterioration and thus prevent leakage, but is not intended to withstand pipeline pressure if the flange gasket leaks. Leak repair clamps, such as those described in U.S. Pat. Nos. 3,603,616 and 4,049,246, are more massive assemblies intended to reduce or eliminate leakage from a flange which otherwise would leak. Because such repair assemblies are intended to withstand high pipeline fluid pressure, the bodies are generally constructed from metallic castings.
The prior art also includes devices intended to serve the dual purpose of a flange protector and a stabilizer between the flanges, such as the device described and claimed in U.S. Pat. No. 3,246,916. The device described therein is capable of resisting substantial lateral forces which may be imposed upon the device by the flange. According to the specification in the patent, however, the device may also be constructed from moldable plastics if the protector is only used to seal the outer peripheries of the flanges. The prior art also includes a pressurized seal device as described in U.S. Pat. No. 2,533,868, which eliminates conventional flange gaskets for flanged pipe sections.
Present day prior art flange protectors are generally of the type described in U.S. Pat. No. 2,271,549. Such flange protectors are intended to protect the sealing ring or flange gasket from the environment, and in part such protection is accomplished by injecting a protective lubricant through the flange protector and into contact with the seal.
Prior art flange protectors of the latter type also have several significant drawbacks. First, these flange protectors can create a severe safety hazard if the flange gasket or seal leaks. In that event, the pipeline pressure subjects the metal outer band of the gasket to high forces, which may cause the metal band to break apart, thus hurling the protector at a high speed toward personnel or other equipment. In part due to the safety hazards associated with flange protectors of the type described in U.S. Pat. No. 2,271,549, such devices have not been widely accepted in industry. Moreover, such prior art flange protectors frequently do not function to maintain the protective fluid under pressure for extended periods of time. Finally, such prior art flange protectors are not easily installed on a flange, and are difficult to install and reuse on other flanges since the metal band frequently becomes bent to the extent that the inner rubber band no longer seals against the flange surfaces.